In modern life, skin is attacked by various factors outside the human body; these are, in particular, atmospheric pollution, ultraviolet radiation, either of natural or artificial nature, or other stresses such as mechanical or chemical stresses.
On account of the ever-increasing occurrence of these problems, in particular in highly urbanized areas, skin protection has become a predominant aspect of the search for novel cosmetic products. In response to attack or to sensations of attack on the skin, the concept of a calmant cosmetic product has been developed.
According to European Economic Community counsel directive No. 76/768/EEC of Jul. 27, 1976 modified by directive No. 93/35/EEC of Jun. 14, 1993, the term "cosmetic product" refers to any substance or preparation intended to be placed in contact with the various surface parts of the human body (epidermis, pilous and hair system, nails, lips and genital organs) or with the teeth and the oral mucosae in order, exclusively or mainly, to clean them, fragrance them, modify their appearance and/or correct body odours and/or protect them or keep them in good condition.
In general, the term "calmant product or calmant cosmetic formulation" refers to any product in formulation which gives a sensation of well-being of the skin, whether this is, in particular, a sensation of softness, of elasticity and/or of comfort experienced by the individual by applying the product to his or her skin.
The Applicant has discovered that all of these stresses on the skin induce a pre-inflammatory state.
During this state, various events occur, in particular the production of free radicals and the synthesis of various pro-inflammatory enzymes, such as elastase. These two phenomena (production of free radicals and of elastase) will not only maintain and propagate this state of inflammation, but will also have harmful consequences on the skin. The production of free radicals, for example, is responsible for the death of many cells, on account of the deleterious effects induced in particular in primordial molecules such as DNA, lipids or proteins; as for elastase, it degrades elastin, the main protein in dermal support. These two phenomena will thus reflect the events which occur during an inflammation, as well as the harmful effects on the skin resulting therefrom.
The Applicant has thus sought to develop a composition which is effective, on the one hand, against the cutaneous stress caused by external attacking factors on the skin, in particular against the harmful effects caused by enzymes which maintain and develop the inflammatory process, and, on the other hand, by inhibiting the process for the production of free radicals.
Compounds of lipoamino acid structure, such as, for example, those described in the international patent applications published under Nos. WO 92/20647, WO 92/21318, WO 94/26694 and WO 94/27561 are, on account of their amphiphilic structure, biological vectors which are particularly advantageous as regulators of skin physiology and prove to be suitable for a large number of applications, in particular in cosmetics.